Hey all - 2000 Ram Van 1500 with 5.2L and 200k miles.

I recently replaced the PCM to solve an idle stall and P0505 error. The new PCM solved the errors and the van now drives great. But today, going downhill at about 30mph with low or no acceleration, it stalled again. No engine light. No error code.

I disconnect and reconnect the positive battery terminal. No engine light. No error codes. Engine turns but won't start, and gauges are all dead.

I fiddle around frantically on side of road. Starter feels strong but engine won't catch. For a second, I see 'No Bus' on odometer display

I disconnected the positive battery terminal, disconnect three wire connectors at the PCM, reconnected connectors at PCM, and reconnected battery, And it started right up.

Any ideas?

Also, my positive battery terminal has a big gouge in the side of it. Like that since I bought the van a few months ago. Seems like that connections corrodes much faster than it should. How big a deal is that?

 

That's not corrosion, that's arcing. (electrical discharge machining.....) I would replace the battery, and the battery cable ends as well....

 

Thanks HeyYou! And yes, that's the damage to the terminal, not the corrosion. I removed the powdery corrosion stuff before taking the photo. Is this battery really toast just from that notch on the terminal? It's super strong otherwise.

On the stalling issue, it seems like it's PCM related. I'm able to recreate the symptom by jiggling the right-most (black) wire connector on the PCM with the engine running. About 50% of the time, I can get the engine to die by jimmy-ing that connect. So adding some zip-ties to see if it's that simple.

Thanks again!

 

If it still works..... you can run with it, but, I would be REAL curious what was going on that caused it to eat that hole in it.

 

Hey all,

Still fighting this No Bus stalling issue. Battery and cable ends have been replaced, per recommendation.

Here's what I've learned about my fabulous No Bus issue...

Van starts right up. But once it warms up to operating temperature, whether driving or idling under a tree, it will die suddenly without warning or any mechanical symptoms. Engine shuts off, power steering and brakes go, and I have a mild heart attack. After 20 seconds, it displays No Bus on the odometer. While in this No Bus mode, the scanner can't pick up any codes or make connection to the PCM, all dashboard gauges are buried at zero, and fuel warning light is on. All other electrical systems (power windows, lights, wipers, horn) work fine.

Sometimes fiddling with the three PCM connectors (specifically the right-most black one) will wake the van back up. You hear the relay click and the fuel pump prime, after which the gauges are all functional and the van starts up. Other times, fiddling does nothing. But waiting half an hour will resolve the issue without ever touching anything. Relay clicks, fuel pump primes, gauges start working again and van starts up. I have de-pinned, inspected, and cleaned all three connectors. Issue persists.

While in No Bus mode, both wires delivering power to the PCM (pins A2 and A22) show 12V when back-probed. Both grounds (pins A31 and A32) have good continuity to ground. Both 5V reference supply wires (pins A17 and B31) show 0.4V, same as at the Throttle Position Sensor, until either time or wiggling the PCM connectors brings the van back to life and the 5V reference returns. I've unplugged the IAC, MAP, TPS, Camshaft, Crankshaft, Governor Pressure, and Rear Wheel Speed sensors while in No Bus mode, and none of them change the 0.4V reference voltage at the TPS.

Any advice on next steps?

If anyone read this far, they're a saint. Thanks so much for any help to can share!

 

I had a somewhat similar issue which turned out to be the insulation worn through on an intake manifold bolt. This was the 5 volt reference to the cam position sensor. Don't know why heating up would short it out, nor why cooling down would work again.

 

Bad solder joints in the PCM.....

 

Thanks HeyYou - so I just got a new PCM installed (actually, it's the original PCM which came with the van, but now repaired by SoloPCM to eliminate a P0505 error). Van starts up fine, no error codes or CEL, and idles happily for about 10-20 minutes. However, when the engine coolant temperature gets up to between 80-92*C, the van will suddenly stall as if the key was turned off. This can be reliably recreated. As soon as the temperature (measured with a scanner and the dash gauge) gets up between 80-92*C (176-195*F) No sputtering or fighting to stay idling. It just dies instantly. CEL flashes once right when it happens, but no error code gets stored and I never see the dreaded No Bus. As soon as the van dies, I hear the relay click and the fuel pump prime, and the van starts right back up without trouble and no waiting. Then it will die after about 2 minutes idling, then again after 1 minute, then again after 30 seconds, etc.

I've replaced the PCM three times now, each time with a new and novel stalling issue. ASD relay is new. Crank position sensor is new (Mopar)

At a loss again. What the heck am I dealing with here??

 

Does temp whig out when it gets to that point? Can you still read the PCM data when it dies?

 

Temp gauge on the dash is still accurate. On my scanner, I need to back out of the temperature graph, but when I open it back up again, it reads correctly.